Expected Performance of MnRoad

Composite Pavements

Michael I. Darter, PE

Applied Research Associates, Inc.

August 23, 2010

MnRoad Open House

Presentation

• Performance measures

• Initial performance results

• Prediction of future performance

– HMA / RCA

– EAC / RCA

– EAC / LCC

• Summary

Performance Measures• HMA surface on Recycled Aggregate

Concrete (RCA): Initial & over Time

– Smoothness, IRI

– Texture depth

– Noise

– Friction

– Rutting

– Fatigue Cracking (transverse, longitudinal)

– Joint Reflection Cracking (HMA)

• No treatment

• Saw & Sealed joints cut in HMA

Performance Measures

• Instrumentation results (not exactly

performance measures, but affect they

may performance)

– Temperature gradations

– Moisture gradations

– Dynamic strains (from moving wheel loads)

– Vibrating wire strains (temperature &

moisture)

Performance Measures

• EAC surface of Recycled Concrete

Aggregate (RCA) & Low Cost Concrete

(LCC): Initial & over Time

– Smoothness, IRI

– Texture depth

– Noise

– Friction

– Fatigue Cracking (transverse, longitudinal)

Initial Results: Noise

Surface

Sound Intensity

Level

HMA ???

Exposed Aggregate Concrete 101.7 dBA

Conventional Diamond Grind of EAC 100.4 dBA

Next Generation Concrete Surface

(Special grinding) of EAC

98.8 dBA

Initial Smoothness: IRI

Surface IRI, in/mile

HMA ???

Exposed Aggregate Concrete ???

Conv. Diamond Grind of EAC ???

Improved Diamond Grind of EAC ???

Results to be obtained from MnRoad soon.

Initial Texture, inchesASTM E 965

Surface Texture

Depth, in

HMA 0.334

Exposed Aggregate Concrete 0.784

Conv. Diamond Grind of EAC 1.127

Next Generation Diamond Grind of

EAC

To be

measured

Initial Friction

Surface Friction

HMA 0.656

Exposed Aggregate Concrete 0.615

Conv. Diamond Grind of EAC 0.720

Improved Diamond Grind of EAC 0.547

Prediction Future Performance

• AASHTO Mechanistic-Empirical Pavement

Design Guide

– Overlay design procedure for HMA OL of JPCP &

Bonded Concrete OL of JPCP

– Use for new composite pavements?

• Some limitations, but with proper inputs can be used.

– Inputs for new composite pavements for 3 MnRoad

sections

• Thickness designs were intended for practicality

of two layer constructability. They are not

intended for long life.

Experimental Plan for Construction at MnROAD

144 m (474 ft)

Clay Subgrade

152-mm (6-in) PCC, 4.6-m (15-ft) joints

32-mm (1.25-in) dia. dowels driving

lane, nondoweled passing lane.

Recycled PCC

433 m (1420 ft)

76-mm (3-in) HMA (S & S joints

except for a few joints)

76-mm (3-in) Granite

(~145 m (475 ft) diamond grind; ~145 m (475 ft) exposed aggregate)

203-mm (8-in) Class 5 Special (Granular Base)

289 m (947 ft)

152-mm (6-in) PCC, 4.6-

m (15-ft) joints, 32-mm

(1.25-in) dia. dowels.

Recycled PCC

(84 m, 275 ft)

152-mm (6-in) PCC, 4.6-m (15-ft) joints,

32-mm (1.25-in) dia. dowels.

Low-cost (high fly ash content) PCC

(205 m, 672 ft)

Cell 70 Cell 71 Cell 72

MEPDG Inputs

• Traffic: I-94 WIM data

• Climate: Nearest weather stations

• HMA: Test data from MnDOT.

• Concrete: EAC, RCA, LCC test data from

FHWA mobile trailer.

• Subgrade: test data from MnDOT &

backcalculation of modulus

• Design: joints, dowels, joint spacing,

thickness of layers, shoulders

MEPDG Inputs

• Traffic: I-94 WIM data MP 200 WBL

– AADT: 29,000

– Percent Class 4 to 13 trucks: 12

– Percent trucks outer lane: 78%

– Axle load distribution: Used MEPDG defaults,

need to obtain MnDOT WIM measured on I-

94 at MP 200.

MEPDG Inputs

Vehicle Classification DataVehicle Class Percent Vehicles

4 2.55 12.76 4.27 0.88 3.49 66.9

10 4.211 1.712 0.813 2.5

Total 100

Climate (5 Weather Stations)

21.9 miles MINNEAPOLIS, MN - CRYSTAL AIRPORT Lat. 45.04 Lon. -93.21 Ele. 872 Months: 101 (C)

25.0 miles ST CLOUD, MN - ST CLOUD REGIONAL AIRPORT Lat. 45.32 Lon. -94.03 Ele. 1024 Months: 116 (M1)

32.0 miles MINNEAPOLIS, MN - FLYING CLOUD AIRPORT Lat. 44.5 Lon. -93.28 Ele. 922 Months: 100 (C)

34.9 miles MINNEAPOLIS, MN - MINPLIS-ST PAUL INTL ARPT Lat. 44.53 Lon. -93.14 Ele. 874 Months: 116 (C)

39.2 miles ST PAUL, MN - ST PAUL DWTWN HOLMAN FD AP Lat. 44.56 Lon. -93.03 Ele. 711 Months: 116 (M6)

MEPDG Inputs• HMA materials data

– PG Grade: 64-34

– Percent asphalt: 5.4 % by weight (assume

10.8% by volume)

– Percent inplace air voids: 5.5 % measured

– Density: 148 pcf

– Gradation of HMA

• Retained on ¾ in = 0%

• Retained on 3/8 in = 20%

• Retained on #4 = 40%

• Passing #200 = 4.3%

MEPDG Inputs

• Concrete: EAC, RCA, LCA test data

Test EAC RCA LCC

Flexural

Strength, psi

854 psi 677 548

Modulus of

Elasticity, psi

4.9 M psi 4.9 M psi 5.1 M psi

Coef.

Expansion

5.6/F 5.8/F 5.4/F

Poisson’s

Ratio

0.23 0.25 0.23

Layer Thickness(from cores)

Section HMA / RCA EAC / RCA EAC / LCC

Top Layer 3.0 in 3.5 in 2.9 in

Bottom Layer 6.3 in 5.6 in 6.7 in

MEPDG Inputs

• Unbound base course:

– 8-in thick

– Class 5 granular base per MnDOT

specifications.

– Used default of 18,000 psi.

MEPDG Inputs

• Subgrade: FWD tested on top of slab &

backcalculation of subgrade modulus

(dynamic k-value, kd)

• Mean backcalculated k-value = 140 psi/in.

• Corresponding Input Mr = 14,000 psi at

optimum density and water content gives

k-value output of about 140 psi/in. This Mr

is about the default for A-6 soil.

MEPDG Inputs

• Design:

– Joint spacing: 15-ft

– Joint sealing: None, single saw blade cut

– Dowels:

• Driving lane: 1.25-in diameter, 12-in spacing

• Passing lane: No dowels

HMA/RCA Predictions

• MEPDG outputs:

– Slab fatigue transverse cracking

– Rutting of HMA

– IRI

• Other potential distress

– Transverse saw and seal joints

3-in HMA / 6-in RCA Section

Saw & Seal Transverse Joints

Slab Cracking, 3-in HMA / 6-in RCA

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

Pe

rce

nt

sla

bs

cra

cke

d, %

Pavement age, years

Predicted Cracking

Rutting, 3-in HMA / 6-in RCA

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 36 72 108 144 180 216 252 288 324 360 396

Ru

ttin

g D

ep

th (

in)

Pavement Age (month)

Permanent Deformation: Rutting

AC Rutting Design Value =

0.5

Total Rutting Design Limit =

MEPDG Prediction HMA / RCA

Age / Trucks % Slab Cracking Rutting, in

Smoothness

IRI, in /mile

0 0 0 63

5 years

3 million

0.3 0.09 94

10 years

6 million

1.2 0.13 100

15 years

10 million

2.7 0.17 107

Reflection cracking of transverse joints: controlled by saw and seal.

HMA / RCA Composite after

10 years and 6 million trucks• Transverse Cracking < 5 % slabs.

• Rutting < 0.10 in. mean.

• IRI < 125 in/mile.

• Two layer HMA over RCA composite

pavement should be in good condition

after 10 years and 6 million trucks in

driving lane.

– Major question: will saw and seal of

transverse joints hold up?

EAC / RCA Predictions

• MEPDG outputs:

– Slab fatigue transverse cracking

– Transverse joint faulting

– IRI

3-in EAC / 6-in RCA

3-in

EAC

6-in

RCA

8-in

Agg.

Base

3-in EAC / 6-in RCA

3-in EAC / 6-in LCC

Slab Cracking, 3-in EAC / 6-in RCA

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

Pe

rce

nt

sla

bs

cra

cke

d, %

Pavement age, years

Predicted Cracking

Joint Faulting, 3-in EAC / 6-in RCA

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

Fau

ltin

g, in

Pavement age, years

Predicted Faulting

IRI, 3-in EAC / 6-in RCA

0

50

100

150

200

250

300

350

400

450

500

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

IRI,

in

/mil

e

Pavement age, years

Predicted IRI

MEPDG Prediction EAC / RCA

Age / Trucks % Slab Cracking Joint Faulting, in

Smoothness

IRI, in /mile

0 0 0 63

5 years

3 million

0.8 0.02 82

10 years

6 million

2.7 0.05 103

15 years

10 million

5.9 0.07 125

EAC / RCA Composite after

10 years and 6 million trucks• Transverse Cracking < 5 % slabs.

• Joint faulting < 0.10 in. mean.

• IRI < 125 in/mile.

• Two layer composite concrete pavement

should be in good condition after 10 years

and 6 million trucks in driving lane.

EAC / LCC Predictions

• MEPDG outputs:

– Slab fatigue transverse cracking

– Transverse joint faulting

– IRI

Cracking, EAC / LCC Predictions

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

Pe

rce

nt

sla

bs

cra

cke

d, %

Pavement age, years

Faulting, EAC / LCC Predictions

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

Fau

ltin

g, in

Pavement age, years

Predicted Faulting

IRI, EAC / LCC Prediction

0

40

80

120

160

200

240

280

320

360

400

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

IRI,

in

/mil

e

Pavement age, years

Comparison RCA & LCC

Property

Recycled Aggregate

Concrete, RCA

Low Cost Concrete,

LCC

Cement, pounds 360 240

Flyash, pounds 240 360

Compressive Strength, psi 4300 5062

Flexural Strength, psi 665 650

Modulus Elasticity, psi 4.8 million 5.1 million

Coefficient of Thermal

Expansion, per degree F

5.8 5.4

MEPDG Prediction EAC / LCC

Age / Trucks % Slab Cracking Joint Faulting, in

Smoothness

IRI, in /mile

0 0 0 63

5 years

3 million

0.2 0.02 78

10 years

6 million

0.7 0.03 95

15 years

10 million

1.6 0.05 112

EAC / LCC Composite after

10 years and 6 million trucks• Transverse Cracking < 5 % slabs.

• Joint faulting < 0.10 in. mean.

• IRI < 125 in/mile.

• Two layer composite concrete pavement

with “cheap” concrete lower layer should

be in good condition after 10 years and 6

million trucks in driving lane.

What If?30-year Design: 23 million Trucks

• 3-in HMA / 8-in RCA

– No structural fatigue cracking

– HMA would need replacement at 8 to 15

years depending on:

• Saw and seal transverse joints: will these hold up?

• Rutting of HMA

What If?30-year Design: 23 million Trucks

• 3-in EAC / 8-in RCA

– No structural fatigue cracking

– Some joint faulting and roughness.

– EAC should perform with no problems: good

friction, no significant wear.

– Diamond grinding should perform with no

problems: good friction, low noise.

30-year Design: 23 million Trucks

• 3-in EAC / 8-in LCC

– No structural fatigue cracking

– Some joint faulting and roughness.

– EAC should perform with no problems: good

friction, no significant wear.

– Diamond grinding should perform with no

problems: good friction, low noise.

Summary

• Construction quality of each section

appears to be good.

• Material properties as expected.

• Initial performance measures reasonable.

• Future performance predictions show

longer than expected life for HMA/RCA

and EAC/RCA and less for EAC/LCC.

• Actual monitoring over time will provide

proof of concept.